OTSUKI (AFP) - Japanese rescuers found five charred bodies in a highway tunnel that collapsed on Sunday, crushing cars and triggering a blaze, and sparking fears of another cave-in.At least seven people were missing inside the nearly five-kilometre (three mile)-long tunnel. Witnesses spoke of terrifying scenes as at least one vehicle burst into flames, sending out clouds of blinding, acrid smoke.For several hours rescuers were forced to suspend their efforts to reach those believed trapped under the more-than one tonne concrete ceiling panels that crashed from the roof as engineers warned more debris could fall.Emergency crews who rushed to the Sasago tunnel on the Chuo Expressway, 80 kilometres (50 miles) west of the capital, were hampered by thick smoke billowing from the entrance.Dozens of people abandoned their vehicles on the Tokyo-bound section of carriageway, and ran for one of the emergency exits or for the mouth, where they huddled in bitter winter weather.Emergency crews equipped with breathing apparatus battled around a third of the way into the tunnel, where they found 110 metres (yards) of concrete panels had come crashing down, crushing at least two vehicles.Hours after the collapse, engineers warned the structure could be unstable, forcing rescuers to halt their work as a team of experts assessed the danger.It was during this inspection that accompanying police officers confirmed the first deaths."What we found resembled bodies inside a vehicle, they were blackened. We have visually confirmed them but have yet to take them out for closer examination," an official told AFP.The Fire and Disaster Management Agency later confirmed there were five bodies, adding another vehicle had also been burned.One man who fled the tunnel told the Jiji Press news agency he had watched in horror as concrete crashed down onto a vehicle in front of him, leaving little more than a mound of dust and debris.Voices cried out "Help" and "Anyone please help" from the pile before a young woman emerged with her clothes torn, he was reported as saying.She could not stop trembling, he told the agency, as he asked her how many had been inside the vehicle. "She said: 'All of my friends and my boyfriend...Please help them,'" said the man, adding the flames were too strong.Footage from security cameras in the late afternoon showed large concrete panels in a V shape, apparently having collapsed from the middle, with teams of men in protective gear scrambling over them.. Japan has an extensive web of highways with thousands of tunnels, usually several hundred metres long. Millions of cars use the network every day.